Unlike many people, I don't like The Walking Dead TV series. Perhaps it's an innate loathing of story lines that mindlessly bludgeon you with drama (subtlety is key to any decent drama), perhaps I'm just over the mindless zombie obsession in pop culture and the assumption of the entertainment industry that zombies can make anything better (more than likely it's the latter). Half way through the first season I would call a friend over whenever an episode aired, and we'd spend an hour going Statler and Waldorf on the episode until the season was finished ... and then I dropped the show.
My friend read the original comic book which the TV series was based on, and though I didn't like that work much either, it was more ambivalence I felt than the active loathing I feel for the TV show.
Then I found out they had made a point-and-click adventure game based on the series. I will admit I haven't played the game, though all the reviews have been positive thus far, and when the game follows a completely different story from the TV series, it's hard to go wrong.
This, however, brings me down to the point: To be successful, entertainment must not always cross mediums. What defines success tends to vary from person to person and whether or not it made back the money put into the original budget. But for the sake of this article we'll go by how successful an adaption is as far as staying true to the original.
Video Games to Movies
Anyone who spent the 90s playing video games will know this to be true. Ever since the early 90s, when people started catching on that video games were going to be a very big, very profitable industry, Hollywood was looking to cut itself a slice of that pie. What has followed since has been a veritable smörgåsbord of horribly made video game movies, and if you ask any gamer about these they will either rage, weep or vehemently deny their existence. The 90s alone gave us the travesties that were Super Mario Brothers, Double Dragon, Street Fighter and Mortal Kombat; for the new millennium we've had Tomb Raider, Doom, Resident Evil, Prince of Persia and another horrible Street Fighter movie (among many others). I truly do wish I could think of some redeeming examples here, but just look at what I have to work with. Not a single movie there with over a 50% approval rating, and most of them financial flops.
Books to Movies
If you thought I was harsh on video game movies, you haven't seen anything yet. I'm far more critical when it comes to book adaptions, and this will count comic books as well. Here is another fine category with many horror stories to it's name. Many that lurk here have been financial successes, but as far as adhering to the book they were based on they fail completely. The first that come to mind are Jaws and Jurassic Park, as both gutted the dark undertones of the book plots for the sake of cutting the movie length. Both had excellent visual effects (Especially Jurassic Park) but any time the plot went deep in the book Steven Spielberg dropped a bulldozer full of rubble in to fill it up. Also here are the likes of Memoirs of a Geisha, The DaVinci Code, The Punisher, Bicentennial Man and Catwoman. A butcher with a blunt cleaver couldn't butcher things worse.
This category does have it's successes though. The Lord of the Rings trilogy leaps to mind, having introduced a new generation to the art of Tolkein, as well as One Flew Over The Cuckoo's Nest, The Godfather, The Shawshank Redemption, Fight Club and the entire Harry Potter series. While I’ll be the first to admit that it’s damn near impossible to create a perfectly accurate book-to-movie adaption for the singular reason of pacing and length, most of these films stay truer to the original work than most.
Books to TV shows
Here is probably the most successful adaptation category. TV isn't usually favored for adaptions for larger titles so hunting down both good and ill produces only short lists. Unlike movies, which only have a few hours to convey an entire story while keeping the audience's attention, a TV show can spread a single book's plot over several seasons and take it's time in the telling. Still though it has it's stinkers. As I already lit into The Walking Dead above, I'll give it some mercy and not mention it again. This category is where medium crossing has been most successful, but even then it has it's failures. Aside from The Walking Dead in here lurks the likes of Game of Thrones (Which I do like both as a book and TV series, but the TV series often is a poor adaption of the books), the above mentioned failure and The Andromeda Strain. Success stories include Boardwalk Empire, M*A*S*H, Bones, House of Cards and I, Claudius.
To be sure, crossing mediums can be produce both financial and quality success stories, and I tend to be very very picky about adaptions (blame the 90s video game movies). However it is rarely a guaranteed thing, and as many of the above examples show shouldn't always be done for the sake of the original work.